Are there any restrictions, or incentives, to develop and sell tools and plugins for the Unity engine? Is there a marketplace to offer these tools? And have anyone here made a 3rd party tool or plugin, who can share his/her experiece?
Thnaks! 
There are 2 that I know of off the top of my head, Fractscape and GUIX.
As far as I know there are no restrictions⌠the incentives might be to help the community and make some money 
Ethan
StarManta also has some middleware. The marketplace is here, more or less (plus whatever you come up with for a web site of course). The main drawback being that when your topic scrolls off the page, people will have a harder time knowing about it. Was there some vague hint that UT might offer 3rd-party space on their resources page eventually, or did I imagine that?
âEric
Thanks
I donât remember hearing anything about that, but that would be really cool if true.
Youâre partially imagining things. Weâve mentioned an interest in having 3rd party content available from the Resources area on unity3d.com, but those would have to be free items, not paid for items. There is some value in a common âmarketplaceâ for such tools and technologies, but thatâs not likely to be our Resources area in particular. There are other ideas afoot but there all way too early to discuss in any way, suffice it to say we think that there is a ton of potential for this kind of business and weâre trying to think of smart ways to enable folks (both sellers and consumers).
Darn those voices in my head! Nice that youâve had some thoughts in this area, though.
âEric
Yay! Would that include âlink-wareâ? In my licenses I grant free use profit and non-profit as long as my logo is displayed.